Wednesday, July 20, 2005

Wastewater treatment can be divided into 3 stages - preliminary treatment, primary treatment, secondary treatment. Preliminary treatment consists of physical screening of large objects. In Primary treatment, the wastewater is held in a separation tank to allow particles to settle to the bottom and grease to float to the top. The solids are drawn off the bottom and skimmed off the top and sent for further treatment as sludge. Secondary treatment is a biological treatment to remove dissolved organic matter from the wastewater. Aerobic microorganisms are allowed to consume the dissolved organic matter. For this purpose, sufficient oxygen have to be provided and this is where aeration comes in. For more details, links to other websites are provided below: